1. Field of the Invention
This invention relates to a hook-and-loop fastener comprising two layers of fabric which are releasably interengageable. One of the fabric layers carries hook- or mushroom-shaped male elements engageable with loop female elements on the other fabric layer. The present invention is concerned more particularly with the latter type of fabric which is formed by warp-knitting into a tape carrying thereon a multiplicity of pile-loops or female elements.
2. Prior Art
Numerous hook-and-loop fasteners commonly known as velvet clasp fastener or more recently termed "surface-type fasteners" have been introduced in the art. A typical hook-and-loop fastener having a warp-knit support tape structure is disclosed in Japanese Patent Publication No. 57-381, in which threads are formed into individual, discrete pile-loops extending over or between rows of stitches and aloof from a foundation web as shown in FIG. 5 of the accompanying drawings wherein the pile-loops are designated at P and the foundation web at F.
A similar warp-knit surface-type fastener tape is disclosed in Japanese Patent Publication No. 55-38121, which tape comprises warp threads, weft threads, pile-loop threads P and elastic threads E, as shown in FIG. 9 of the accompanying drawings. The elastic threads E serve to make the tape stretchable with pile-loops extending in floating relation to the foundation web in a manner similar to the tape disclosed in Japanese Patent Publication No. 57-381.
Both of the above prior art warp-knit female tapes have a common drawback in that since the pile-loops are independent one from another and kept in free disposition, they are prone to tilt or otherwise become deformed; that is, they fail to retain the desired shape and position that have been afforded upon fabrication of the tape, resulting in insufficient or defective coupling engagement with the hook elements on the mating male tape.